So what you need to do is, to take the names of the input fields and place them into that line of code. The file is in this example called send_mail.php

Code:

<?php
$yourMail = "your@email.com"; //The email address you want to receive mails on
//stuff from the html form
$name = $_POST['name']; //Grap the name from the name field
$email = $_POST['email']; //Grap the email from the email field
$comment = $_POST['comment']; //Grap the comment from the comment field
//the magic part
mail($yourMail, $name, $email. $comment);
?>

THIS IS JUST AN EXAMPLE for you to understand
Now please notice that it would be a really bad idea to use this code, since it is vulnerable to injections. So you would want to do something in the lines off